\Header{tmd}{Tukey Mean-Difference Plot}
\keyword{dplot}{tmd}
\begin{Description}\relax
Create Tukey Mean-Difference Plots from a trellis object returned by
\code{xyplot} and \code{qq}\end{Description}
\begin{Usage}
\begin{verbatim}
tmd(object, xlab = "mean", ylab = "difference", ...)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{object}] An object of class ``trellis'' returned by
\code{xyplot} or \code{qq}

\item[\code{xlab}] x label
\item[\code{ylab}] y label
\item[\code{...}] other arguments
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
The Tukey Mean-difference plot is produced by modifying the (x,y)
values of each panel as follows: the new coordinates are given by
\code{x=(x+y)/2, y=y-x}.

Most arguments given to produce object are transmitted to \code{tmd},
with the notable exceptions of \code{aspect} and \code{scales}. (This
behaviour is different from S-Plus.)\end{Details}
\begin{Value}
An object of class ``trellis''. The `update' method can be used to
update components of the object and the `print' method (usually called
by default) will plot it on an appropriate plotting device.\end{Value}
\begin{Author}\relax
Deepayan Sarkar \email{deepayan@stat.wisc.edu}\end{Author}
\begin{SeeAlso}\relax
\code{\Link{panel.tmd}}, \code{\Link{xyplot}},
\code{\Link{Lattice}}\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
data(singer)
tmd(qqmath(~height|voice.part, data = singer))
\end{ExampleCode}
\end{Examples}

